To not go too deep let’s limit ourselves to AUFS storage driver. Now it should be obvious where this Dockerfile fails at optimizing image size.Īnyway let’s take a deeper look so that we understand how are those yum caches removed from image layers.

each Dockerfile instruction generates a new layer.

each layer has its own UUID and each successive layer builds on top of the layer below it.

Docker image is a tagged hierarchy of read-only layers plus some metadata.

Let’s look once more at our brief recap of images and layers: Well, the second RUN command has no desired impact on image size even if it looks as it should shrink the image. An alternative option is to use the docker save command to get a good approximation of the compressed size.RUN yum -y install java-1.8.0-openjdk-devel-1:1.8.0.7_1.x86_64 If you are building Docker images and want to get an ideal of what the compressed size, you could push it to a registry and then utilize the technique describe in the previous Docker Registry Image section to retrieve the compressed size, but that can be wasteful and/or undesirable.

In this example, the compressed size of the /dotnet/core/samples:dotnetapp-buster-slim image is 76,411,911 bytes (74.6 MB). > docker manifest inspect /dotnet/core/samples:dotnetapp-buster-slim īy adding up the config and layer sizes you will get the total compressed size of the image.

See experimental docker features for more information. At the time this article was written, the docker manifest command is in experimental and must be enabled. To do this you can utilize the docker manifest command.

If the image resides in a registry, you can retrieve the size of the image without pulling it locally. Measuring the compressed size of a Docker image depends on where the image resides - in a Docker registry or locally. The example commands shown below will work on Windows, MacOS, and Linux. This affects how much local storage is required to support your Docker workloads. Uncompressed size - This is often referred to as the size on disk.This impacts the first run experience on machines where images are not cached. This affects how fast/slow images can be pulled from a registry. Compressed size - This is often referred to as the wire size.There are two metrics that are important to consider when discussing the size of Docker images.

Docker inspect layer size